Reversal process of color photography



multi-layer film of any of said layers.

Patented Feb. 16, 19 43 REVERSAL PROCESS OF COLOR PHOTOGRAPHY Emery Meschter, Milltown. mesne assignments, to E.

N. J., assignor, by I. du Pont de Nemours Company, Wilmington, Del., a. corporation of Delaware No Drawing. Application September 19, 1939, Serial No. 295,686

7 Claims. (Cl. 95-2) .This invention relates to color photography. More particularly it relates to processes of producing dyed reversed images. Still more particularly it relates to processes of producing superposed dye reversed images in multi-layer film. Still more particularly it relates to the production of superposed dyed reversed images in V containing immobile color forming compounds in at least one layer.

This invention has for an object the provision of an improved method of generating dyed reverse images. A further object is to provide dyed rate layers representing the color aspect of a is to produce simultaneously in a multilayer film a plurality of reverse dye images, without resorting to re-exposure Another object is to color develop the middle or buried layer of a multi layer film containing three superposed diflerentially sensitized silver halide emulsion layers without re-exposing the said layer. Other objects include the preparation of a more satisfactory color film,'a reduction in the number of steps required to process a color film, and a general advance in the art.

The above and other objects are accomplished by the following invention which comprises the use of an aqueous dye forming reducing bath containing an aromatic polyamino developing agent containing at least one unsubstituted amino group and a nitrogenous base free from negative groups and hydroxyl groups attached to carbon atoms.

In a more limited sense the objects are attained by the use of aqueous dye forming reducing baths containing an arylene diamino developingagent and a nitrogenous base free from negative groups and hydroxyl groups attached to carbon, in the presence of a color former capable of forming an indophenol or azomethinedyestuif for developing reversed metal salt images especially silver salt images. t

In a still more limited sense, the invention comprises the use of aqueous dye forming reducing bathscontaining arylene diamino photographic nitrogenous bases as previously stated are free dyed images in sepadeveloping agents containing at least one unsub stituted amino group and preferably free from nuclear hydroxyl groups and a nitrogenous base free from negative groups and hydroxyl groups attached to carbon capable of energizing said developing agent so that it no longer distinguishes between exposed and unexposed silver halides in its reducing action for developing reversed silver salt images in photographic elements.

The energizing agents which change aromatic polyaminodev'eloping agents containing at least one unsubstituted amino group and especiallythose free from negative and hydroxyl groups do not fall into any one specific class of bases but fall within numerous classes. The operative from negative groups such as halogen atoms, e. g. Cl, Br: nitro, SOaM, COOM wherein M is H or a metal, and hydroxyl groups, attached to carbon.

The bases which are water soluble or can be readily dispersed in aqueous systems are most effective. Bases which do nothave the above constitution, for'example, the alkylol amines e. g; mono-, diand tri-ethanol amines, do not function in the reducing solutions of the present invention. I

An important class of nitrogenous bases which are organic amines may be represented by the general formula:

wherein each R, R and B" may be hydrogen, alkyl, cycloalkyl, aryl, aralkyl, or wherein two R's may represent a divalent polymethylene hydrocarbon or R, R and R" together may represent a trivalent hydrocarbon radical such as a polymethenyl radical which, with the nitrogen atom, forms-an N-heterocyclic atom.

Another important class of' compounds which are quaternary ammonium bases may be represented by the general formula:

alkyl, cycloalkyl, aryl, aralkyl or wherein two the invention by divalent polymethylene hythree Rs may represent a Rs may represent a drocarbon radical or cyclic trivalent v polymethenyl radical which with the nitrogen atom, forms an N-heterocyciic atom:

Another important class of compounds which are aliphatic polyamines may be represented by the general formula:

R: RI

wherein each R1, Ra, Ba and R4 may be hydrogen, alkyl, cycloalkyl, aryl, aralkyl, and further characterized in that the methylene groups may be substituted'by alkyl, cycloalkyl, aryl and aralkyl groups and at least one of the methylene groups may be substituted by amino groups, and 'n is 1 to 8.

As examples of may be present in suitable alkyl groups which each of the above formulae,

mention is made of methyl, ethyl, propyl, isoerai formula:

or a water soluble salt thereof, wherein R and hydrocarbon radical such as a.

a-naphthyl, Bnaphthyl, etc.

tioned benzyl, 2-methyl benzyl, naphthyl-methyl,

reducing V of which has been employed to produce a metallic. silver image corresponding to the latent image.

The residual silver salts or' reversed image can first be fireed of the initially developed silver image by means of the well-known bleaching and clearing baths but are preferably directly treated in the dye generating reducing baths described herein in the presence of color formers, especially those capable of'formlng indophenol or ammethine dyes.

The reversal processes hereof as previously stated, are of utility in the processing of multilayer film, including monoand multipacks composed of difierentially color-sensitive photographic emulsion layers. They are of especial utility in processing monopacks comprising at least three differentially color-sensitive silver halide emulsion layers, each containing immobile color formers, which are borne by a transparent base member. One of the layers may be placed on one side ofthe base and two on the other. The layers may be separated by clear layers, e. g. colloid layers such as gelatin which prevent migration of color formers, sensitlzers,

which may be dyed toact as temporary filter layers.

A preferred embodiment of the invention involves the reversal processing of multilayer film R are the same ordiflerent lower-alkyl radicals,

e. g. methyl and ethyl; and a nitrogenous base free from negative groups and hydroxyl groups and falling within one oi the Formulae 1, 2, and 3.

One important embodiment of this invention is concerned with the use of aqueous baths of the above type for the treatment of multilayer film composed of three superposed difierentially sensitized silver halide emulsion layers containing immobile color former compounds which form colors complementary in color to the employed sensitivity range of the respective emulsion layers. This embodiment will be more fully described below.

In another embodiment of the invention the above baths modified by the addition of color formers which are soluble in' aqueous solutions or can be readily dispersed therein are used for the development of reversed images, particularly reversed silver halide images in at least one layer of a multi-layer film. i a

The reversal process of this invention may be used with a wide variety of difierent types of film structure. The processes, however, all involve the development of a latent image or series of partial latent images corresponding to a scene including colored scenes, in an ordinary noncolor-forming photographic developer. The residual silver salts represent a reversed image since they are the counter-part residue of a given amount of silver halide coating, a certain p rtion Bath A I p-Amino-N-diethylaniline grams 2 Ammonium hydroxide, conc cc 25 Sodium sulfite, anhy-,.-'. grams 2 Water to liter 1 Both 3 ep-Aminodiethylaniline migraine-. 2

Hexamethylenediamme (55% in meth anoll re 15 Sodium sulflte, anhy .grams 3 Water to v ter..- i

Bath 0 f p-Aminodiethylaniline grams 3 Ammonium hydroxide, con'c ..cc.... 3% Sodium carbonate, anhy grams 2' least one emulsion layer is protected from theaction of light after the first development of a reversal process due to the fact that a layer of pre-fogged silver-gelatino-halide emulsion is interposed between atleast .two' difierentiallv colorsensitized emulsion layers.

in order that the invention will be more readily understood a number of reducing baths which can be used for processing film containing color formers will be described... These baths which are of general utility are claimed in copending application of E. Meschter, Serial No. 295,635, entitled Reducing Baths, filed upon an even dateherewith.

Waterto li er.. 1

image to metallic silver silver bromide emulsion.

, tral region 2-amino-5-diethylamino-toluenegrams.

The following examplesare directed to various processes involving the reduction of a silver salt with the use of. color.-

i'ormers in emulsions. It is to be distinctly uns I derstood that the following examples are merely illustrative of the nature oi the'inventi'on and are not intended tolimit' it in any way.

Example I A monopack comprising a cellulose acetate-film base suitably subbed is coated with a gelatino sensitized to red so as to exhibit very little sensitivity in the green specby means of a green'blind sensitizing dye, e. g. pinacyanol. To this blue-red sensitive emulsion layer is added 15 grams of a non-migratory blue-green color-former, e. g. a salicyclaldehyde-o-sulfobenaaldehyde acetal oi polyvinyl alcohol per 1,000 grams of emulsion. Over this blue-red sensitive layer is coated another-silver halide emulsion layer which is sensitized to the blue-green region of thespectrum with a sensitizingdye, e g, erythrosin, and contains-a magenta (minus green) color former, e. g. i-(mstearoyla'minophenyl) 3-methyl 5 pyrazolone,

Over the last-mentioned layer is coated a layer of gelatin solution containing a removable yellow filter dye, e. g. Tartrazine C. I. 640. Over the yellow filter layer is coated a blue sensitive silver halide emulsion containing a yellow color former,

e. g. furoyl-acetbenzoylacet-benzidide.

The above-described fllm element is exposed to a colored object scene whereby latent images representing diflerentcolor component aspects in the diii'erent sensitive layers are formed as is known in the art. See, for. instance, Schinzel Austrian Patent No. 42,478. The film is then processed by the following steps:

Trimethyl-benzyl=ammoniumhydroxidemci- 20 Sodium sulfite. anhy -grams 5 Water to v l er" 1 Bath G 4:4-diaminodiphenylamine grams 4 Hexamethylenediamine ..do 10 Sodium sulfite, anhy do. 2 Water to er" 1 Bath H 1 :4-diaminonaphthalene "grains" 3 Dimethylcyclchexylamine cc 30 Sodium sulfite, anh'y -grams 3 Water to er... 1

Bath '1 4-diethylamino-1-naphtliylamine grams 5 B-dimethylannnoethylamine cc- 20 Sodium sulflte, anhy grams 5 Water to liter, 1

' Bath] p-Aminodibutylaniline--- "grams" 3 Hexamethylenediamine solution in methanol) grams 20 Sodium sulfite, anhy do 2 Water to er 1 Bath K -p-Aminodiethylaniline grsms 3 Trimethyl-benzyl-ammoniumhydroxide cc 25 Sodium su1fite,anhy grams 3 Water to 'lif.er 1.

pre-foeged emulsion containing a yellow (minus 1. Develop 10 minutes in an ordinary metolhydroquinone positive developer.

2. Wash 10 minutes.

3. Reduce residual silver salts by treating for 15 minutes in a dye-generating reducer oi the following formula:

Sodium sulfite, anhydrous grams p-aminodiethyl aniline dihydrochloride grams" 2.0 Hexamethylene diamine (40 solution) cc 20 Water to lif.4=r 1 4. Wash 10 minutes.

5. Bleach minutes in a solution containing ti by weight of potassium ferricyanide and made alkaline with ammonium hydroxide or sodium carbonate.

6. Rinse.

7. Remove bleached silver in a 25% solution of hypo (crystalline sodium' thiosulfate).

8. Wash 15 minutes and dry.

The color photograph resulting from the above process is of exceptional clarity and brilliancy. The saturation of dyes or dye densities is considerably greater than that obtained by known methods of processing. The images have very good resistance to fading, particularly under action of ultra violet radiation.

Example II A cellulose acetate film base is coated with a 30 mg. coating of a silver bromide emulsion sensitized to the red region of the spectrum with a green-blind, red sensitizing dye, e. g. a naphthiocarbocyanine,. containing a blue-green color former of the type set forth in Example I. Over this layer is coated a 25 mg. coating of silver bromide which was precipitated ln the presence of the normal amount of gelation with about 0.5 gram of allyl thioureaper kilogram of final emulsion, said emulsion being digested for one hour at 120 F.'and.the remaining gelatin added and dissolved. Over the pre-fogged layer is applied a 35 mg. orthochromatized silver bromide emulsion containing 5 grams of the magenta color-former of Example I. Another coating of blue) filtering material, e. g. 6 grams of titanium ierrocyanide yl-a-pyrldinium stearyl bromide, was superposed on said orthochromatized layer. Over this prefoeged filter layer is coated a 38 mg. coating of blue sensitive high'contrast silver chloro-bromide emulsion containing about 8 grams of a'yellow col r former. e. 8. dlbenzoylacetbenzidide.

The just described multilayer film is exposed to a colored scenewhich may be from an optical image or the image produced from a color transparencyaccording tothe steps ofreversal process set forth in Example I. using, however. in

or 4 grams of 4-piperonylbutadien- I '8; McQueen, Serial'No. 233,480, filed emulsion, silver salt in the pre-fogged layers and the togplace of the reducer described in Step 3, the following reducer:

Soduim sulfite, anhydrous "grams" "p-Aminodiethyl aniline dihydrochloride grams Sodium carbonate, anhy do.. 20 Ammonium hydroxide, conc cc 30 ,,Water in "litelr 1 The resulting film was of exceptional clarity and brilliancy and the dye images of good density.

In place of the specific dye-forming reducing baths of the'preceding examples may be substituted a wide variety of reducing baths having the above-described characteristics. Thus, any of the baths described in the aforedescribed application may be substituted with similar result.

Similarly, various other immobile color form ers, may be substituted for formers which give excellent results include nonmigratory yellow color-formers, which may be used in the blue-sensitive layer, as follows: diacylacetamino-aryl-bis-thiazoles of U. S. Patent 2,140,540, of which difuroylacetamino-1,2,4,5- benzoebis-thiazole and di-acetoacetamino4,2,4,- 5-benzobisthiazole are especially useful as are 2- hydroxy 3 naphthoylaminobenzoyl-acetanilide,

- 924), 4,4'-methylene-bis-(mqstearoylaminophem yl)-methyl pyrazolone (described in Jennings, Serial No.256,201, filed February 13, 1939), and 4A-'o-sulfo-benzylidene-bis-(phenyl methyl pyrazolone) (described in Jennings, Serial No.

256,201, filed February 13, 1939). I

Suitable non-migratory blue-green color formers of especial utility include 4,4'di -(1-hydroxy- 2-naphthoyl-amino) diphenyl, l-hydroxy-2-car- 'b'oxy-5-dodecoylamino naphthalene,

l-N-stearoyl--N-(Y-oxy-Z' naphthoyl) phenylenedi amine sodium sulfonate, resorcinol mono-n-dodecyl ether (described in Salzberg 8a White-U. S. Patent No. 2,166,181 (filed September 21, 1937),

product of p-hydroxybenzoic acid and formaldee hyde (described in' McQueen, Serial No. 261,-. 794, filed March 14, 1939), product of polyvinyl alcohol and salicyaldehyde (described in Doroll'gh October 5, 1938) Example HI e A multilayer film so disposed that light after passing through an optical aperture is first incident on a blue-sensitive silver halide emulsion containing a yellow filter dye such as Luxol Fast Yellow "1, then a pre-fogged emulsion layer, then a green sensitive emulsion, another pre-fogged emulsion layer'containing a soluble red dye, e. g. carmosine M, then a red sensitive silver halide and finally the base. The amount of ging' exposure given the layers is such that upon the specific color, formers set forth in the above examples. Color I Sodium sulfite, anhy grams Water to I the first development of the layers a light barrier layer will be formed therein so that substantially less than 1% of light will be transmitted by either of them. 1

In using thisfilm, it is exposed normally in a camera, and then developed in a non-color-forming developer. the film containsthree'color separation negative image layers bearing both silver and unexposed, undeveloped, silver-salt images, and two layers of metallic silver. The film is now preferably exposed through the base with a red or white printing light which exposes only thesilver salt image remaining in the red sensitive layer. The red light does not substantially eflect the other two layers because of their lack of sensitivity to the red light used as the printing light, and sec-- ondly, the black metallic silver barrier layer prevents substantially all of the printing light from passing through to the outer layers.

The film is now developed in a dye forming reducing bath of the following composition:

2:3:4-trichlor-a naphthol grains 2-amino-5 diethylaminotoluene do Potassium carbonate"; ccs.

liter 1 prepared by dissolving the trichlornaphthol in alcohol and adding the other ingredients-to water and bringing the solution up to one liter, whereby a blue-green (minus-yellow) dye image and silver image is formed. The film is then thoroughly washed. I

The top or blue sensitive layer is then exposed to a blue or preferably a white printing light. This printing light does not afiect the middle layer because of the metallic silver barrier layer between the top and middle layers. The entire film is then treated with a yellow (minus-blue) color-forming developer of the following composition 2 Potassium carbonate grarns 4.0

Sodium sulfite, anhydo 5 Diethyl-parapheynlenediamine hydrochloride o Water to 1 to which is added the following solution:

Benzoyl acetone-3 grams dissolved in 25 cc. of ethyl alcohol.

After development, the blue-sensitive layer will contain both metallic silver and yellow dye images. It is then thoroughly washed.

The green-sensitive middle layer or both sides of which are black, metallic silver barrier layers,

remains. This layer istreated in a dye-forming reducingbath of the type herein described con= taming an arylene diamino compound and a nitrogenous base and a magenta color former. A

suitable bath is composed of Thioindoxyl-carboxylic acid ..grams 2 p-Amino-N-diethylaniline do fl-Dimethylaminoethylamine cc 20 Sodium sulfite, army; grams 3' Water to liter 1 Example IV A multilayer film comprising a transparent i support coated on one side first with a 35 mg.

coating of foggd"silver-gelatino-bromide emu"- sion and a layer of orthochromatized emulsion is coated on the logged emulsion layer. On the other side of the support is coated first a 30 mg. layer of silver bromide emulsion, sensitized to the red After development and washing I under baths A to K.

of two outer layers.

. treatment.

region but not to the green region, and containing an immobilized blue-green indo-phenol-. forming dye component and over this is coated a 30 mg. layer of blue-sensitized silver chloride emulsion dyed with Tartrazine, C. I. 640.

After exposure to a natural colored scene. the above film is developed in an ordinary metolhydroquinone developer of the type usually employed for positive film development and then washed. The following processing stages are then given the film:

. l. The orthochromatized layer is flashed with to which is added the following solution:

Benzoylacet-p-amino-N-phenyl morpholine, 3 gramsdissolved in 25 cc. of ethyl alcohol 6. Wash.

7. Immerse film in one of reducers described 8. Wash. i 9. Bleach in alkaline potassium ferricyanide solution.

J 10. Wash. i ll. Fixinplain, 25%, hypo solution.

12. Wash and dry. The film and process described above ofi'ers I the advantages:

A. It affords a possibility of controlling the exand therefore, dye-density characteristics 13. The middle or buried layer is not proc- 'essed by a developer, partially exhausted from having first developed an upper layer.

C. The middle or buried layer receives most energetic reduction, therefore outside layers can be flashed accordingly heavy.

The energetically working reducer applied to reduce the middle or buried layer will also probablyreduce silver halides in'the other layers whichwere not developed by the color-forming developers, however, since only the buried layer contains a color-former, no additional color is formed in the outside layers. The additional siloutside layers ls'removed along ve'r reduced in the with the silver images in the ferricyanide-hypo Example V A photographic support, which may be a transparentfilm or a paper base and suitably subbed, is coated with a 30 mg. layer of silver bromide I emulsion, sensitized in the red but not the'green regions, and containing 30 grams of salicylaldehyde-phthalaldehydic acid acetal of polyvinyl alcohol per kilogram of emulsion. Over this is'coated a thin separator layer of plain 75 gelatin and on this is applied a 35 mg. layer of silver bromide emulsion sensitized into the green region and containing 24 grams l-(m-stearoylamino-phenyl) -3 -methyl-5-pyrazolone per kilo- 5 gram of emulsion. Over the green sensitive layer is coated another thin separator layer or plain gelatin and over this is coated a gelatin layer containing a yellow screening dye such as Tartrazine O, C. I. 640 or 4-piperonylbutadienylalpha-pyrldinium-stearyl bromide. yellow filter layer is applied a 25 mg. coating of chloro-bromide emulsion containing grams of dibenzoyl acet-benzidlde.

After exposure to a colored scene, the above film is processed as in Example I. The colorgenerating reducing bath for this film is that given as Bath C in the series of energized reducing baths listed above.

20 Example VI The dye-generating reducing baths of the present invention are particularly suited for the mass production of color photographs on paper by the use of multilayer stripping films, the individual layers of which containindophenol, azomethine and azo dye-forming components. Such films are fully described in copending Marasco application, Serial No. 245,274, entitled Photographic films, now Patent No. 2,182,184. A preferred form of color stripping paper can be prepared by coating a double-weight, photographic paper support with an acid-stripping layer from the following solution:

Grams Piperidylmethylzein 4.0 Chrome alum 0.2 Acetic acid (glacial) 4.75

' Ethyl alcohol (65% water) 91.0

On this is applied a thin coating of ethyl cellu- 40 lose dope:

Grams Ethyl cellulose 5.0 Methyl acetat 77.0 Acetone 11.7 Xylene 6.3

, This thin film support is suitably subbed and then coated with a layer of silver chloro-bromide emulsion sensitized in the red but not in the green region. Red sensitizing dyes which give absolutely no sensitizing action in the green region are described in Middleton and co-pending application, Ser. No. 174,114, now Patent No. 2,270,378. This green-blind, red sensitive layer contains approximately 20 grams of octadecyl ether of resorcinol per kilogram of emulsion as the blue-green color-forming compound. On the red sensitive emulsion layer is coated another thin film layer of ethyl cellulose, suitably subbed and then coated with a subbing layer and then a coating of green sensitized silver chloro-bromide emulsion containing 1 4:4'-bis- (3' '-methy1-pyrazo'lonyl-1 -biphenol.

Another acid stripping layer of piperidylmethyl zein is applied over the green sensitiye layer, followed by a thin ethyl cellulose coating which is then subbed to receive a blue sensitive silverchloride emulsion containing Tartrazine 0 asthe yellow filterdye and dibenzoylacetbenzidide as the yellow color-forming material.

printed by exposing th:ough a colored positive transparency, which is preferably of the colorline ,or color-grain type, with a printing light suitably filtered so that it transmits three sharp- Over the Jennings The above-smiltilayer color stripping fllm'ls track. With the spectral .by first covering only the water-proof lacquer, a suitablecoating compo.

sition for which is:

unit Ethyl alcohol.

ly defined color bands each within the corresponding transmission band of the color element of the .color screen. After exposure, the stripping film is developed in a contrasty Metolhydroquinone developer, washed, reversed in a suliamic aeid-dichromate bleach bath as de scribed in McQueen -co-pending application, Serial No. 233,117, now Patent No. 2,195,149, cleared in a sodium sulfite solution, and washed. The combined stripping iilms lose their anchorage during the bleaching operation and are then stripped off and transferred to temporary supports, such as glass plates. The residual silver salt images remaining in each or the three layers are then reduced to metallic silver by means of one of the baths listed under A to K with the concomitant formation of respective dye images and the silver images are removed as previously indicated. The stripped layers are then superposed in register on a suitable white,

paper support. The advantages ofiered by the present process over troloi dye-density and dye-gamma values atiorded by controlling the time of treatment by the dye-generating reducing baths. .Since the increase in dye-density with these reducers conprevious methods is the con- I tinues over a much longer period of time than I with ordinary co1or+developers, the resulting dye-gamma values can be varied over a wide range, thus afiording the opportunity to prepare color-prints of time chromatic rendition. 1

The energetim action of the dye-generating reducers described previously provides an improved means for processing the sound record areas of films for the production of colored sound films. An exemplary procedure appears below.

In the normal arrangement of sensitized emulsion layers and color-forming compounds, and particularly with the introduction of sound recording systems employing ultra-violet radiation as the recording radiation, the sound record is placed in the upper portion of the uppermost emulsion layer and, methods, would finally appear as a wellow sound response of photoelectric tubes and the dye-gamma characteristics of yellow color-for compounds as they under ordinary processing.

are, it is desirable to process the sound area to blue or black rather than yellow.

' Example vn Using a multilayer as described in Example V, the is exposed so as to contain ccmplemental latent images in the various emulsion layers an thelatent sound record image 1 a in the uppermost layer, by layer-localized printing from master separation positive records and ultra-violet printing or the sound record.

The picture-and-sound is then processed sound area with a Per cent l by weight Ethyl cellulose (ethom content 2.50 molslca 98 2 This protective layer dries rapidly and him is then processed as follows:

methylpiperidine,

aaiassi I 3. Reduce residual picture silver halides with dye-forming reducing bath D. v

4. Wash and blow-off surface water.

5. Bathe in ethanol to remove protective ethyl cellulose coating.

6. Develop sound track in metol-hydroquinone developer.

'7. Wash.

8. Reduce residual with bath K in which has been dissolved 5 grams of a-naphthol.

'9. Wash.

10. Bleach and remove silver images.

11. Wash and dry.

By the above method it is possible to produce continuous lengths of cinematographic bearing natural color picture images and single-color sound records in continuous processing machines and their water-soluble salts, e. g. chloride, sulfate, acetate, oxalate, etc.

Similarly, other basic compounds which cause the above developing agents to become overall reducing agents may be substituted in whole or in partfor the specific bases set forth above. Thus, one or more of the following may be used: Lower alkylamines such as mono-, diand trimethyi, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, etc. amines, which contain no negative groups, especially hydroxyl groups in the hydrocarbonradicals; straight and branched chain alkyl monoand poly-amines free from nuclear negative, especially hydroxy groups, e. g. ethylenediamine, tetramethylenediamine, hexamethylene diarnine, triaminopropane, p-dimethylamino 'ethylamine, n-propylamylhexylamine, tri-n-amylamine, di-isoamylam'ine, cyclic and heterocyclic amines, e. g. piperidine,

ethylpiperidine, piperazine, N- dimethylcyclohexylamine, N ethyl N methyl cyclohexylamine, n-oetyl-pyridinium hydroxide; quaternary n-hydroxides free from nuclear substituted negative groups especially hydroxyl groups, a. g. I 1

Trimethylbenzylammonium-hydroxide Tetramethylammoniurn hydroxide n Dodecyldimethylcyclohexylammonium droxide n-Dod'ecyltrimethylammonium hydroxide n-=Octadecylbenzyldimethylammonium hydroxide n-Dodecylphenyldimethylammonium hydroxide sound area silver halides.

set forth in the above B-naphthoy1 acetone, acetoacetic esters,

groups and hydroxyl groups attached to carbon which may be used in practicing this invention are further characterized in that they have an association exponent (pkab) of about 5.00 to about 12.00 and prefe ably from 9.00 to 11.40. The proportions of the components of the reducing solutions may be varied considerably. For instance, the amount of arylene-diamino developing agent may vary from 2 to 12 grams per liter with good results. The amount of alkali metalor ammonium sulfite may vary from 5 to 25 grams per liter of solution. The amount of weak alkali, e. g. sodium carbonate may vary from to 30 grams per liter. With regard to the nitrogenous base free from negative groups and hydroxyl groups, it may vary from 8 to 30 grams or ccs. per liter of solution.

Likewise, other color forming compounds may.

be substituted for'the specific ones set forth in the above examples or may be used with any of the herein disclosed arylene diamines. As examples of representative suitable color-formers which are soluble \or readily dispersible in the reducing solutions are diacylacetamino-aryl-bisthiazoles ofU. S. Patent 2,140,540, of which difuroylacetamino-1,2,4,5-benzo bis thiazole is preferred, the acylacetarylides of U. S. Patent 2,108,602, acetyl acetone, benzoyl ethyl-achloroacetoacetal, ethyl 'y chloroacetoacetate, ethyl malonate, ethyl-p-nitrophenyl-acetate, ethyl propionate, ethyl acetone dicarboxylate, furoylacetic ester, the acylacetamino phenyl morpholines of U. S. Patent'2,133,937, etc.

Suitable magenta color-formers include nitriles, e. g. p-nitrobenzyl cyanide, o-nitro-benzylcyanide, p-toluylacetonitrile, w-cyanoacetyl-dibenzfuran, w-cyano-acetyl-acenaphthene, 1-wcyanoacetylcoumarone, 1:3-di- (w-cyanoacetyl) benzene, acyl nitriles, e. g. cyanacetophenone, methoxy-a-naphthoylaceto-nitrile, cyanacetanilides, e. g. 1-cyanacetamino-benzthiazole, etc., pyrazolones, I e. g. 1-phenyl-3-fury1-fi-pyrazolone, 1 phenyl 3 -carboxylic acid pyrazolone, 1-phenyl-3-hydroxy-5-imino-pyrazolone, 1-(8'- quinolyl) -3-methyl-5-pyrazolone, 1 phenyl-3- methyl-5-thiopyrazolone, etc.

Suitable blue-green color formers include phenols, e. g. ortho and meta-chlorphenol, o-bromophenol, o-iodophenolf naphthols, e. g. 2,3,4- trichlomaphthols, 2,6-dibromo 1,5 dihydroxy .naphthalene, etc.

An important advantage of the present in-' vention resides in the fact that the readily available weak arylene diamino types of developing agents may readily be converted into powerful reducing agents in a simple manner and with the aid of inexpensive and readily available additional agents.

A further advantage'resides in the fact that a weak developingagent of the arylene diamine type becomes readily converted into an excellent color developing agentproducing a much greater dye density for the same amount of reduced acetone,

silver by theaddition of inexpensive and readily available photographic materials. Any 'suitable developers of the type used as the first developer in a reversal process can be used for the development of the negative images.

An energetic working developer is preferably used to give full detail and harmonious color rendering. It is' also desirable that the developer selected produce-a minimum 'of relief effect in the gelatin. To this end, caustic alkalies should instance, is suitable as the developing agent, as are also acid amidol developers where the films do not contain color-formers. The development at this stage should be carried out completely,

, that is none of the latent images should be left undeveloped. I A suitable developer for the above purpose is Developer-A Metol grams 2.5 Hydro'quinone do 9.0 'Sodium sulfite, anhy do 75.0 sodium carbonate, anhy do 50.0 Potassium bromide do 3.5 Water to l r" 1 tion which is of major importance. The elimination of one or more steps means that a shorter processing time is required. A more simplified continuous developing machine may be used. A substantial savings of chemicals, wash water costs, etc. is efiected.

The present invention provides an improvement over previous suggestions for reversal development, wherein residual silver halides are chemically exposed by means of sulfur bearing compounds such as thiourea, allyl thiourea, etc. since these proposals incur the need for additional tubes or tanks in processing machines,

more wash water consumption and an extended total processing time. Furthermore, such compounds are undesirable because of their obJec-,

tionable odor.

A further advantage resides in the fact that a much greater density of dye image is produced with the same silver-density as compared with the usual colordevelopers containing alkaline carbonates as pH regulators.

An additional advantage resides in the fact that a very great increase in the coupling velocity of color formers is obtained by the use of the baths containing arylene diamino compounds and certain nitrogenous bases as energizers. Still other advantages will be apparent to thoseskilled in the art.

, As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments hereof except as defined in the appended claims.

I claim:

1. A photographic reversal process comprising developing a photographic element containing a latent image in an ordinary developer to produce a negative image and developing the reversed image without re-exposure in the presence of a color former with an aqueous reducing bath containing a compound of the general formula:

bon atoms ,in an amount sumcient to change the characteristics of the solution so that it no longer I r I are members. of the group prises developing a photographic element containing a latent image in an ordinary developer to produce a negative image and developing the reversal image without re-exposure in the presence of a color former with an aqueous reducing bath containing an aromatic primary amino developing agent and an aliphatic amine of 1-8 carbon atoms in an amount suflloient to change the characteristics of the solution so that it no longer distinguishes between exposed and unexposed silver salts, said amount being within the range irom 8 cos. to 30 grams per liter of solu tion.

4. A process as set forth in claim 3 wherein said amine is hexamethylenediamine.

5. A photographic reversal process which comprises developing a multilayer. film having three respective layers, which has been exposed to a colored object, in an ordinary developer to produce silver color-component images in the respective layers and simultaneously developing the reversed images without re-exposure in an aqueous reducing bath containing as the sole type of reducing agent an aromatic amino developing agent having an unsubstituted amino group and an aliphatic primary amine of 1 to 6 carbon atoms in an amount'suiiicient to change-the characteristics of the solution so'that it no longer distinguishes between exposed and unexposed silver salts, said amount being within the range from 8 cos. to 30 grams per liter of solution.

6. A process as set forth in claim 5 wherein said amine is hexamethylenediamine.

7. A process as set forth in claim 5 wherein said amine is hexamethylenediamine.

EMERY IMESCHTER.

cxnnmcamm co'mzzcnon. Patent No. 2,510,981. February 16, 19+

" m1?! rmscnmn.

It is hereby certified that error appears in the printed apecificdtion of theabove numbered intent requiring correction as follows: Page 5, sec- 'ond column, line 29, for the patent number'2,l82,l814." read --2,182,8111.--; page 6, first column, line S fOI "2,19 ,3 3" read --2,19 ,1;19--; 11neh5,

for "wallow" read "yellow"; and that the said Letters Patentahould be read with this correction therein that the eame may ccniorm to the record of-the case in the Patent Office.

Signed and sealed this 20th day 6r April, A. D. 1915.

-Henry' Van Arsdale, (Seal) Acting commissioner of Patents. 

